package cn.xaut.XAUT迎春杯预热;

import java.util.Scanner;

/**
 * N - 这里才是入门0.0
 * 考点：二分搜索法
 */
public class demoN {

    static int N, K;
    static double[] a;
    static final double E = 0.001;
    
    // 检查 K 条绳子各分成长度为 len 的小绳子的总和
    static int check(double len) {
        
        int res = 0;
        for (double l : a)
            res += l / len;
        
        return res;
    }
    
    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        N = input.nextInt();
        K = input.nextInt();
        a = new double[N];
        double sum = 0; // 总长度
        for (int i = 0; i < N; i++) {
            a[i] = input.nextDouble();
            sum += a[i];
        }
        double l = 0, r = sum / K, mid = (r + l) / 2;
        if (check(r) == K) {
            System.out.printf("%.2f\n", r);
            return;
        }
        
        while (r - l > E) {
            int res = check(mid);
            if (res >= K)
                l = mid;
            else 
                r = mid;
            mid = (l + r) / 2;
        }

        double res = mid;
        System.out.printf("%.2f\n", res);
    }
}
